Display instrument, in particular in a motor vehicle

ABSTRACT

In a pointer instrument, a LED ( 7 ) is arranged in such a way that light can pass from it into a free end face ( 5 ) of a pointer shaft ( 2 ) which is embodied as a light guide. For this purpose, a printed circuit board ( 4 ) on which the LED ( 7 ) is fitted has an opening ( 6 ) which is flush with the end face ( 5 ) of the pointer shaft ( 2 ) and into which the LED ( 7 ) projects, at least partially.

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a display instrument, in particular in a motorvehicle, which display instrument has a light-guiding pointer which isconnected fixed in terms of rotation to a pointer shaft embodied as alight guide, and a LED which is secured behind the end face of thepointer shaft facing away from the pointer in order to inject light intothe pointer shaft, and thus also into the pointer from a printed circuitboard arranged behind a pointer drive.

Display instruments of the abovementioned type are known, In them theLED is arranged on the side of the printed circuit board facing thepointer shaft, opposite the lower end face of the pointer shaft. Forthis reason, the light which is emitted by the LED only needs to beinjected once into the pointer shaft and deflected once in order to makeit pass into the radially orientated pointer. However, in practise thearrangement of an LED on the side of the printed circuit board facingthe pointer drive often causes problems because the spatial conditionsare very restricted in this region. The problem is aggravated by thefact that LEDs with strong illumination which are necessary to light apointer brightly have a particularly large overall volume.

SUMMARY OF THE INVENTION

The invention is based on the problem of configuring a displayinstrument of the type mentioned at the beginning which is intended fora motor vehicle in such a way that the space required for thearrangement of the LED is as small as possible.

This problem is achieved according to the invention in that the printedcircuit board has an opening opposite the end face of the pointer shaft,and the LED projects into this opening.

As a result of this configuration, the cross section of the printedcircuit board can be at least partially used to receive the LED, withthe result that the LED does not need to project as far, or does notneed to project at all, into the pointer drive, and takes up less spacethere. In order to simplify the orientation of the LED, it is favorableif the opening is arranged flush with the end face of the printedcircuit board.

The fabrication of the display instrument is particularly cost effectiveif the LED is electrically connected to the printed circuit board on theside of said printed circuit board facing away from the pointer driveand projects with a lens into the opening the electrical connection ofsuch a LED can be made by customary soldering.

The space required for the LED is particularly small if the LED iselectrically connected to the printed circuit board on the side of theprinted circuit board facing the pointer drive and projects with itsbase into the opening.

The light can be injected into the pointer shaft in a particularlylow-loss fashion if, in accordance with a further advantageousdevelopment of the invention, the LED is arranged on the side of theprinted circuit board facing away from the pointer drive and a lens ofthe LED which is embodied as a separate component, receives the lightfrom the LED and injects it into the pointer shaft is inserted into theopening.

The lens can be secured particularly tightly to the printed circuitboard and mounted very quickly by pressing or clipping on if it has acircumferential securing edge which can be pressed or clipped onto theprinted circuit board.

The pointer may be illuminated with a color different from that of theLED if the lens has a coloring. Alternatively, it would be possible toconceive of using a comparatively expensive multi-color LED for changingillumination colors.

If the LED is arranged on the side of the printed circuit board facingaway from the pointer drive and projects into the opening, it is thenpossible, in order to avoid light losses, to keep the distance betweenthe injection face of the pointer shaft and the LED very small by virtueof the fact that the pointer shaft engages partially in the opening inthe printed circuit board.

A development of the invention which is advantageous in particular inLEDs with strong illumination provides for the LED to have an elementwhich conducts away heat. This element which conducts away heat is, in aparticularly simple form, a housing of the LED which, for example, ismade particularly large for this purpose. However, special elements forconducting away heat, such as cooling ribs, may also be provided.

According to another advantageous development of the invention, areflector is arranged so as to engage in the opening in the printedcircuit board, which reflector increases the usable proportion of thelight of the LED which can be injected into the pointer shaft. In aparticularly simple way it is possible for this reflector to be pluggedor pressed into the printed circuit board or clipped to the printedcircuit board.

The number of components of such a display instrument according to theinvention can be advantageously reduced if, in accordance with anotherrefinement of the invention, the reflector has an electrical conductingelement for making contact with the LED.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention permits various embodiments. In order to clarify its basicprinciple further, a plurality thereof are illustrated in the drawingand will be described below. In the drawing:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a vertical section through a region of a display instrumentaccording to the invention,

FIG. 2 shows a vertical section, corresponding to FIG. 1, through asecond embodiment of the display instrument,

FIG. 3 shows a section through the region of a printed circuit boardwith an LED and one end of a pointer shaft,

FIG. 4 shows a section, corresponding to FIG. 3, through a modifiedembodiment,

FIG. 5 shows a section, corresponding to FIG. 3, through a furtherembodiment,

FIG. 6 shows a section, corresponding to FIG. 3, through a furtherembodiment with a reflector, and

FIG. 7 shows an alternative embodiment with a reflector according toFIG. 6.

FIG. 1 shows a region of a pointer drive 1 of a display instrument (notillustrated in more detail), for example a tachometer, of a motorvehicle, in which pointer drive 1 a pointer shaft 2 made oflight-guiding material is mounted. This pointer shaft 2 is fitted with apointer 3 which is also light guiding. On the side of the pointer drive1 facing away from the pointer 3, a printed circuit board 4 is arranged,said printed circuit board 4 having an opening 6 flush with the lowerend face 5 of the pointer shaft 2. A LED 7 projects with its base 8 intothis opening 6 from the side of the pointer drive 1, with the resultthat only a lens 9 of the LED 7 projects out of the plane of the printedcircuit board 4. The LED 7 is advantageously operated with a current ofapproximately 50 mA (order of magnitude) and preferably has in thisexample an irradiation angle of approximately 10° on each side of itscenter axis.

In the embodiment according to FIG. 2, the LED 7 is arranged on the sideof the printed circuit board 4 facing away from the pointer drive 1 andsoldered to it there. A separate lens 10 is inserted into the opening 6from the side of the pointer shaft 2, which lens 10 is seated on theprinted circuit board 4 and injects the light from the LED 7 into thepointer shaft 2.

As is shown by FIG. 3, the separate lens 10 may have a circumferentialsecuring edge 11 which is pressed or clipped into the printed circuitboard 4 with the result that the lens 10 is secured particularly tightlyto the printed circuit board 4.

FIG. 4 shows that the LED 7 is seated on the printed circuit board 4from above with conductors 12, 13.

FIG. 5 shows that the pointer shaft 2 can project with a shoulder 14into the printed circuit board 4 with the result that its lower end face5 is particularly near to the LED 7.

FIG. 6 shows the LED 7 arranged on the side of the printed circuit board4 facing away from the pointer drive (not illustrated here), the lens 9projecting into the opening 7 in the printed circuit board 4. Areflector 15 with securing arms 17 being pressed into the printedcircuit board 4 and causing the light emitted by the LED 7 to convergebefore it enters the pointer shaft 2.

FIG. 7 shows how the reflector 15 can be formed by means ofthrough-contacts 16 for making electrical contact with the LED 7 throughthe printed circuit board 4.

We claim:
 1. A display instrument, in particular in a motor vehicle, which display instrument has a light-guiding pointer which is connected fixed in rotation to a pointer shaft embodied as a light guide, and a LED which is secured behind an end face of the pointer shaft facing away from the pointer in order to inject light into the pointer shaft, and thus also into the pointer from a printed circuit board arranged behind a pointer drive, wherein the printed circuit board (4) has an opening (6) opposite the end face (5) of the pointer shaft (2), and the LED (7) projects into said opening (6).
 2. The display instrument as claimed in claim 1, wherein the LED (7) is electrically connected to the printed circuit board (4) on a side of said printed circuit (4) facing away from the pointer drive (1) and projects with a lens (9) into the opening (6).
 3. A display instrument, in particular in a motor vehicle, which display instrument has a light-guiding pointer which is connected fixed in rotation to a pointer shaft embodied as a light guide, and a LED which is secured behind an end face of the pointer shaft facing away from the pointer in order to inject light into the pointer shaft, and thus also into the pointer from a printed circuit board arranged behind a pointer drive, wherein the printed circuit board (4) has an opening (6) opposite the end face (5) of the pointer shaft (2), and the LED (7) projects into said opening (6), wherein the LED (7) is electrically connected to the printed circuit board (4) on a side of the printed circuit board (4) facing the pointer drive (1) and projects with a base (8) thereof into the opening (6).
 4. A display instrument, in particular in a motor vehicle, which display instrument has a light-guiding pointer which is connected fixed in rotation to a pointer shaft embodied as a light guide, and a LED which is secured behind an end face of the pointer shaft facing away from the pointer in order to inject light into the pointer shaft, and thus also into the pointer from a printed circuit board arranged behind a pointer drive, wherein the printed circuit board (4) has an opening (6) opposite the end face (5) of the pointer shaft (2), and the LED (7) projects into said opening (6), wherein the LED (7) is arranged on a side of the printed circuit board (4) facing away from the pointer drive (1) and a lens (10) of the LED (7), is inserted in the opening (6) said lens being formed as a separate component, receives light from the LED (7) and injects it into the pointer shaft (2).
 5. The display instrument as claimed in claim 4, wherein the lens (10) has a circumferential securing edge (11) which can be pressed or clipped onto the printed circuit board (4).
 6. The display instrument as claimed in 2, wherein the lens has a coloring.
 7. A display instrument, in particular in a motor vehicle, which display instrument has a light-guiding pointer which is connected fixed in rotation to a pointer shaft embodied as a light guide, and a LED which is secured behind an end face of the pointer shaft facing away from the pointer in order to inject light into the pointer shaft, and thus also into the pointer from a printed circuit board arranged behind a pointer drive, wherein the printed circuit board (4) has an opening (6) opposite the end face (5) of the pointer shaft (2), and the LED (7) projects into said opening (6), wherein the pointer shaft (2) engages partially into the opening (6) of the printed circuit board (4).
 8. A display instrument, in particular in a motor vehicle, which display instrument has a light-guiding pointer which is connected fixed in rotation to a pointer shaft embodied as a light guide, and a LED which is secured behind an end face of the pointer shaft facing away from the pointer in order to inject light into the pointer shaft, and thus also into the pointer from a printed circuit board arranged behind a pointer drive, wherein the printed circuit board (4) has an opening (6) opposite the end face (5) of the pointer shaft (2), and the LED (7) projects into said opening (6), wherein the LED (7) has an element for conducting away heat.
 9. A display instrument, in particular in a motor vehicle, which display instrument has a light-guiding pointer which is connected fixed in rotation to a pointer shaft embodied as a light guide, and a LED which is secured behind an end face of the pointer shaft facing away from the pointer in order to inject light into the pointer shaft, and thus also into the pointer from a printed circuit board arranged behind a pointer drive, wherein the printed circuit board (4) has an opening (6) opposite the end face (5) of the pointer shaft (2), and the LED (7) projects into said opening (6) and further comprising a reflector (15) arranged so as to engage in the opening (6) of the printed circuit board (4).
 10. The display instrument as claimed in claim 9, wherein the reflector (15) has an electrical conductor element (16) for making contact with the LED (7).
 11. The display instrument as claimed in 4, wherein the lens has a coloring. 